Unit 1: Flashcards
The Question of Differentiation
Since every cell in the body contains relatively the same genes, how can so many different cell types be generated
The Question of Morphogenesis
How can the cells in our body arise to functional structures?
Pattern Formation
Spatial organization of cells
Microsurgery
Putting cells in new situations, or even transplanting pieces of one cell to itself or others.
The Organizer
Spemann/Mangold
Which piece of the blastopore induces formation?
The Dorsal lip
Vogt
Created the concept of fate mapping
Germ layers (3)
Ectoderm, Mesoderm, Endoderm
Gametes
Sperm and egg
Blastomeres
small cells that make up a blastula
Gastrulation
When the blastula undergoes rapid cell rearrangement, formation of the three germ layers
Germ cells
cells set aside for reproductive information
Somatic cells
Non-germ cells
Life cycles are usually controlled by:
Environmental factors, such as seasons [temp]
Blastocoel
Fluid filled space in the animal hemisphere of the blastula to allow for extensive cell movement during gastrulation
Blastopore
Dimple on the embryo surface which marks the dorsal side. Cells entering will become the mesoderm
Notochord
rod of mesodermal cells most dorsal position to become nervous system
Neurula
Embryonic stage where notochord has formed
Somites
precursors to back muscles,spine, and dermis
Comparative Embryology
How anatomy changes during development of different organisms
Evolutionary Embryology
How changes in development cause evolutionary change, and how ancestry affects the current organism
Teratology
Study of birth defects
Oviparity
birth from egg [amphibian]
Viviparity
live birth[mammal]
Ovoviviparity
birth from inside an egg[chick]
Ectoderm [2 tissues]
Skin, and brain/nervous system
Endoderm[2 tissues]
Digestive tract, and organs coating
Mesoderm[7 tissues]
Blood,heart,kidney,gonads,bones,muscles,connective tissues
Describe the Organizer experiment
One dorsal blastopore was transplanted to a new embryo which then contained two dorsal blastopore. Both areas started developing gastrulation and neurulas, notochords, and neural tubes, and eventually two organisms attached together.
Induction: Definition
The process by which one cell or tissue induces a specific reproducible differentiation in another tissue or cell.
Describe “Sufficiency” and how it does not have to be necessary.
Sufficiency means that an added element is enough to create the entire change, however, the element itself is not necessary to finish that change. The change could occur naturally without the added element. Example: Bill Gates vs. the Lottery. In order to be rich, you do not have to be Bill Gates, but being him would be sufficient.
Describe how “sufficiency” relates to functional redundancy. What does this mean for a cell?
Having components that are sufficient, but not necessary for a process allows for completion even when an element may fail, another is sufficient.
Describe “Necessity” and how it does not necessarily mean the element is sufficient.
An element may be needed to complete a task, but it doesn’t mean that the element alone can complete the task. For example: Air and water. Air is necessary for survival, but air alone can also not guarantee survival. Water is also needed.
Does the Organizer experiment show that cells are Sufficient, or Necessary?
Sufficient. The cells alone put in a different situation created the same result without help.
Specification: Definition
The extent to which a cell is predestined to become a specific type for differentiation, or not.
Autonomous Specification
A cell is predestined a long time ago, and has reproducible divisions. Associated with localized determinants
Autonomous Differentiation Example
Poking off specific cells in Ascidians created mollusks of that cell type
Conditional Specification
Late decisions, variable divisions, regulative development, interactions with neighboring cells determine differentiation
The Organizer: Autonomous or Conditional Specification
Autonomous, because removed from a place, and still did the same thing.
Genomic Equivalence: Definition
Each somatic cell has the same chromosomes
Differential Gene Expression
Each cell has the capability to express the entire genome, but only a few are actually expressed.
Places of gene regulation
Nuclear RNA, messenger RNA, protein translation, choice of functional proteins within cell
Histone Methylation
Addition of negative charge to histones causes unraveling of DNA and allowing transcription
DNA Methylation
Stops transcription factors from binding
Chromosome puffs
in drosophila, all cells contained the same chromosomes, but only the puffed region [different in each cell] was being transcribed
Dolly the Sheep
Oocytes were denucleated, and nucleus of other sheep added. Implantation into surrogate mother, and successful birth
Histones
DNA wrapped stones within the chromosome chromatin complex
Describe the process of nuclear transfer
An egg’s nucleus can be removed, and a different nucleus inserted into the egg with different DNA.
As the age of the nucleus increases, successful development …
decreases
Why is Cloning so Rarely Successful?
LOS, Placental Defects,histones, epigenetic
Therapeutic Cloning
Using cells to create stem cells to differentiate
Reproductive Cloning
Cloning for human creation.
Chimeric Mixture
Splitting an embryo at its 8 cell stage or earlier and using multiple genomes
Totipotency
When a cell can differentiate into any other cell type
Pluripotency
When a cell can differentiate into almost any other cell type
Stem cells are harvested from the ___ stage of the embryo
Blastocyst
When can stem cells not from a fetus be found?
Bone marrow, and the umbilical cord
What is compaction, and why is it an important embryo stage?
Compaction is when the 8 cell embryo compacts together. After this, it is not possible for the cells to have totipotency.
Watershed: Implantation Pro
Many embryos fail to implant. Since several will never become born, the embryo at this stage cannot be considered a human.
Watershed: Implantation Con
Under the right conditions, any embryo COULD implant, therefore the embryo at this stage is a human. Also, ex utero development is becoming increasingly possible.
Watershed: Twinning Pro
A blastula can split and become twins later. This split is the start of human individuation, not beforehand, therefore the human blastula is not an individualized human.
Watershed: Twinning Con I
The process of twinning is not that there was once nothing, then suddenly two. There was ONE and now TWO, therefore, there was a complete individuated life in the blastula.
Watershed: Twinning Con II
Cnidarians form asexual polyps on themselves. Was the initial cnidarian not a cnidarian?
Watershed: Neurulation Pro
The defining element of the human species is our advanced nervous system. Therefore the embryo is not a human until the neural system begins to form.
Watershed: Neurulation Con
Under the right conditions, embryos WILL form the CNS. “human with potential” vs. “potential human”
Functionalist View
The functions of something define what it is.
Anti functionalist View
If you are only a human based on what you can function doing, then how do we consider those who are impaired, or infants, or the elderly?
Development is Continuous
The embryo will not articulate itself into any other species. Therefore it is a human. The human blastula is just what we all looked like at that stage of development.
Ontology
finding the essence of what something is
Ethics
What is the nature of good, and what is our responsibility towards it?
Deontological
Duty based, if the embryo is my neighbor, I have certain responsibilities toward it no matter how inherently useful it is
Consequentialist View:
maximize the good for all, even if a few must suffer
Intuitionism
Feels like
Commodification
Making something, such as the human life, into a commodity
Does ontology and ethics always overlap?
No, an example, is abortion. if you think that the fetus is a human life, however, the right of the woman supersedes the life of the unborn child.
Pragmatic Compromise
When the ethical obligations change due to extenuating circumstances, examples include ice babies. [ frozen embryos ]
How did Induced Pluripotency first come about?
Yamanaka factors [retroviral transfection] to create Pluripotency
Teratoma
Ovarian tumors that spontaneously differentiate cells within them , example hair.
How to test the abilities of a iPS
Place in Tetraploid cell that has not inner mass cells. If the embryo succeeds, then the iPS cells were indeed pluripotent.
Transdifferentiation
Direct reprogramming of cells instead of going through a pluripotent stem cell step
cDNA
complimentary DNA
How to find and mark specific parts of DNA
We can uses sequences complimentary to the ones we want as probes with dioxigenin as a place for something to bind to
How to find and mark specific proteins
Use a primary and secondary antibody
Indirect Immunostaining
Synthesize a piece of DNA with a GFP part on it that creates a fluorescent tail to the protein.
